In the scientific study of streams and rivers, it is highly desirable to take accurate readings of the various hydrological parameters of the stream, particularly with regard to flow discharge. These readings must be taken whether the stream is a small, wadable one, or one which is a major river. In addition, measurements must be made for rivers which are completely flowing, as well as those which are covered by a top layer of ice. Although there are many devices for measuring flow in a moving stream, most of them cannot be used for the variety of flow measurements required in different types of streams and rivers.
The prior art includes many devices for measuring underwater flow velocity. Among these are the Price type AA current meter which is used for depths 1.5 feet and deeper. This meter is seldom used through ice cover due to its size. Additionally there is the Price pygmy current meter which is used for depths less than 1.5 feet and which can be used through ice cover due to its small size, and the four-vane vertical axis meter, used on a rod, which also takes flow measurements of streams under ice cover (all disclosed in Buchanan et al., Discharge Measurements at Gaging Stations, U.S. Geological Survey, 1969, pp. 4-7). These devices are generally suitable for specific functions and for specific velocities and depth, but do not work well in other types of stream conditions. What is desired is a current meter which can be employed with a variety of support equipment and which can be used to measure fluid velocity conveniently and accurately in shallow streams, deep rivers, and ice-covered waterways as well.